Which sentence best summarizes the purpose of the Brooklyn Bridge 60,000 ton achorages?

Brooklyn Bridge is suspension bridge on both sides of the East River from Brooklyn to Manhattan Island, New York City. It is a genius feat of 19th century engineering.

The Brooklyn Bridge was the first bridge that used steel for cable wire, and

during its production explosives were used inside a pneumatic caisson for the first time. Eyebars and cables are completely encased in 60,000

tons of stone anchorages of the Brooklyn Bridge. Each anchorage weighs as much

as 12,000 elephants. Concealed inside were four enormous anchor plates. Its main

purpose was to make the bridge six times stronger.